On Thu, Nov 2, 2017 at 4:17 PM, Sudeep Holla <sudeep.ho...@arm.com> wrote: > On 02/11/17 02:39, Jassi Brar wrote:
>>>>> >>>>> Such controllers don't need to transmit any data, they just transmit >>>>> the signal. In such controllers the data pointer passed to >>>>> mbox_send_message is passed to client via it's tx_prepare callback. >>>>> Controller doesn't need any data to be passed from the client. >>>>> >>>> Some controllers need a non-zero value written to a register in order >>>> to trigger the signal. >>> >>> You are right, just right non-zero or whatever controller value to >>> trigger the interrupt to remote. >>> >>>> That register is visible to the remote. While the data/packet is setup >>>> during tx_prepare() callback. >>> >>> Agreed. >>> >>>> You are overlooking this class of doorbell controllers. >>>> >>> >>> Not sure what do you mean by that ? >>> >> Such doorbell controllers can't use send_signal(chan) because they >> need that non-zero value from client to send over the shared register. >> You are assuming every protocol implements just one command. >> > > No that non-zero value is not client specific, it's entirely controller > specific. > ?? For example BCM2835 has such a controller. Have a look at bcm2835_send_data() and let me know what is that controller specific value. >>> Again agreed. But see below for reason to create this API. >>> >>>>> The new API send_signal will eliminate the >>>>> issue Jassi has explained in earlier discussion with respect to generic >>>>> message format using Rockchip example. >>>>> >>>> Sorry I don't see how. >>>> Please explain how can send_signal() api be used by, say, rockchip to >>>> support SCMI? >>>> >>> >>> 80 writel_relaxed(msg->cmd, mb->mbox_base + >>> MAILBOX_A2B_CMD(chans->idx)); >>> 81 writel_relaxed(msg->rx_size, mb->mbox_base + >>> >>> 82 MAILBOX_A2B_DAT(chans->idx)); >>> >>> 83 >>> >>> will be replaced with >>> >>> writel(whatever_value_to trigger_signal, MAILBOX_A2B_CMD(chans->idx)); >>> >>> in its send_signal function. >>> >> 1) Where does the "whatever_value_to_trigger_signal" come from? > > Controller specific. > >> That has to come from client. > > No. > Again, let me know what does the controller expect 'val' to be writel(val, MAILBOX_A2B_CMD(chans->idx)) Your entire post is based on your assertion that the controller expects a particular non-zero value to trigger a signal, which is wrong. So lets first get that straight and not stray from the point.
